Reduced-pressure dressings, systems, and methods employing desolidifying barrier layers

ABSTRACT

Reduced-pressure medical dressings, systems, and methods involve a dressing with a first barrier layer that desolidifies when exposed to a fluid—typically a liquid—to form a treatment aperture in the first barrier that is used to deliver reduced pressure to a tissue site. The first barrier layer is formed from a desolidifying material. The system includes a drape covering a second surface of a manifold and a portion of the patient&#39;s epidermis to provide a substantially sealed space containing a manifold and the first barrier layer. Other systems, dressings, and methods are also disclosed.

RELATED APPLICATION

The present invention claims the benefit, under 35 USC §119(e), of thefiling of U.S. Provisional Patent Application Ser. No. 61/225,604entitled “Reduced-Pressure Dressings, Systems, and Methods EmployingDesolidifying Barrier Layers,” filed Jul. 15, 2009, which isincorporated herein by reference for all purposes.

BACKGROUND

The disclosure relates generally to medical treatment systems, and moreparticularly, but not by way of limitation, to reduced-pressuredressings, systems, and methods employing desolidifying barrier layers.

Clinical studies and practice have shown that providing a reducedpressure in proximity to a tissue site augments and accelerates thegrowth of new tissue at the tissue site. The applications of thisphenomenon are numerous, but application of reduced pressure has beenparticularly successful in treating wounds. This treatment (frequentlyreferred to in the medical community as “negative pressure woundtherapy,” “reduced pressure therapy,” or “vacuum therapy”) provides anumber of benefits, which may include faster healing and increasedformulation of granulation tissue. Unless otherwise indicated, as usedherein, “or” does not require mutual exclusivity.

SUMMARY

Improvements to existing reduced-pressure treatment apparatuses,systems, and methods may be realized by the apparatuses, systems, andmethods of the illustrative, non-limiting embodiments herein. Accordingto an illustrative, non-limiting embodiment, a system for providingreduced-pressure therapy to a tissue site of a patient includes areduced-pressure source for supplying reduced pressure and a manifoldhaving a first, inward-facing surface and a second surface. The manifoldis operable to transfer the reduced pressure. The system includes afirst barrier layer covering at least a portion of the first,inward-facing surface of the manifold. The first barrier layer is forplacement adjacent the tissue site and the first barrier layer is formedfrom a desolidifying material. The system also includes a drape forcovering the second surface of the manifold and a portion of thepatient's epidermis to provide a substantially sealed space containingthe manifold and the first barrier layer.

According to another illustrative, non-limiting embodiment, an apparatusincludes a manifold having a first, inward-facing surface and a secondsurface. The manifold is operable to transfer reduced pressure. Theapparatus also includes a first barrier layer covering at least aportion of the first, inward-facing surface of the manifold. The firstbarrier layer is formed from a desolidifying material.

According to another illustrative, non-limiting embodiment, a method forproviding reduced-pressure therapy to a tissue site of a patientincludes applying a dressing to the tissue site. The dressing includes amanifold having a first, inward-facing surface and a second surface, andthe manifold is operable to transfer reduced pressure. The dressing alsoincludes a first barrier layer covering at least a portion of the first,inward-facing surface of the manifold. The first barrier layer is formedfrom a desolidifying material. The method also includes allowing fluidat the tissue site to desolidify at least a portion of the first barrierlayer to create a treatment aperture and applying a reduced pressure tothe tissue site via the treatment aperture.

According to another illustrative, non-limiting embodiment, a method ofmanufacturing an apparatus for providing reduced-pressure therapy to atissue site of a patient includes providing a manifold having a first,inward-facing surface and a second surface, and providing a firstbarrier layer formed from a desolidifying material. The method alsoincludes coupling the first barrier layer to the first, inward-facingsurface of the manifold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic, cross-sectional view, with a portion shown as ablock diagram, of a reduced-pressure treatment system according to oneillustrative, non-limiting embodiment;

FIG. 1B is a schematic, cross-sectional view of the dressing shown inFIG. 1A in which a portion of the first barrier layer has desolidified;

FIG. 1C is a schematic, plan view of the dressing shown in FIG. 1B fromthe perspective of the tissue site;

FIG. 2 is a schematic, cross-sectional view of a manifold and a firstand second barrier layer shown according to an illustrative,non-limiting embodiment; and

FIG. 3 is a schematic, cross-sectional view of a manifold according toan illustrative, non-limiting embodiment, which has a first and secondbarrier layer in which one of the barrier layers has a plurality ofperforations.

DETAILED DESCRIPTION

In the following detailed description of the illustrative, non-limitingembodiments, reference is made to the accompanying drawings that form apart hereof. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it isunderstood that other embodiments may be utilized and that logicalstructural, mechanical, electrical, and chemical changes may be madewithout departing from the spirit or scope of the invention. To avoiddetail not necessary to enable those skilled in the art to practice theembodiments described herein, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the illustrative embodiments are defined only by the appendedclaims.

Referring now to the drawings and primarily to FIGS. 1A through 1C, areduced-pressure therapy system 100, which includes a reduced-pressuresource 102 and a dressing 104, is shown according to an illustrative,non-limiting embodiment. The dressing 104 includes a manifold 110 and afirst barrier layer 112 that is configured to help avoid maceration ofintact skin and to encourage epithelialization. The dressing 104 isapplied to a tissue site 106, which may include a wound 107, of apatient 108 so that reduced pressure from the reduced-pressure source102 can be transferred to the tissue site 106 via the dressing 104.

As used herein, “reduced pressure” generally refers to a pressure lessthan the ambient pressure at a tissue site that is being subjected totreatment. In most cases, this reduced pressure will be less than theatmospheric pressure at which the patient is located. Alternatively, thereduced pressure may be less than a hydrostatic pressure at the tissuesite. Unless otherwise indicated, values of pressure stated herein aregauge pressures. The reduced pressure delivered may be constant orvaried (patterned or random) and may be delivered continuously orintermittently. Although the terms “vacuum” and “negative pressure” maybe used to describe the pressure applied to the tissue site, the actualpressure applied to the tissue site may be more than the pressurenormally associated with a complete vacuum. Consistent with the useherein, an increase in reduced pressure or vacuum pressure typicallyrefers to a relative reduction in absolute pressure.

The tissue site 106 may be the bodily tissue of any human, animal, orother organism, including bone tissue, adipose tissue, muscle tissue,dermal tissue, vascular tissue, connective tissue, cartilage, tendons,ligaments, or any other tissue. Treatment of the tissue site 106 mayinclude removal of fluids, e.g., ascites, exudate, or delivery ofreduced pressure. The wound 107 on the tissue site 106 may be due to avariety of causes, including trauma or surgery.

The dressing 104 includes the manifold 110 and the first barrier layer112. The manifold 110 includes a first, inward-facing (tissue-facing)surface 114 and a second surface 116. The term “manifold” as used hereingenerally refers to a substance or structure that is provided to assistin applying reduced pressure to, delivering fluids to, or removingfluids from a tissue site 106. The manifold 110 typically includes aplurality of flow channels or pathways that improve distribution offluids provided to and removed from the tissue site 106 around themanifold 110. The plurality of flow channels may be interconnected. Themanifold 110 may be a biocompatible material that is capable of beingplaced in contact with the tissue site 106 and distributing reducedpressure to the tissue site 106. Examples of the manifold 110 mayinclude, for example, without limitation, devices that have structuralelements arranged to form flow channels, such as, for example, cellularfoam, open-cell foam, porous tissue collections, liquids, gels, andfoams that include, or cure to include, flow channels. The manifold 110may be porous and may be made from foam, gauze, felted mat, or any othermaterial suited to a particular biological application. In oneembodiment, the manifold 110 is a porous foam and includes a pluralityof interconnected cells or pores that act as flow channels. The porousfoam may be a polyurethane, open-cell, reticulated foam, such as aGranuFoam® material manufactured by Kinetic Concepts, Incorporated ofSan Antonio, Tex. Other embodiments may include “closed cells.” In somesituations, the manifold 110 may also be used to distribute fluids, suchas medications, antibacterials, growth factors, and various solutions tothe tissue site 106. Other layers may be included in or on the manifold110, such as absorptive materials, wicking materials, hydrophobicmaterials, and hydrophilic materials.

The dressing 104 also includes the first barrier layer 112 that coversat least a portion of the first, inward-facing surface 114 of themanifold 110. The first barrier layer 112 is disposed adjacent to thetissue site 106 such that the first barrier layer 112 is disposedbetween the manifold 110 and the tissue site 106. The first barrierlayer 112 may be fixedly or non-fixedly attached to the manifold 110.For example, the first barrier layer 112 may simply abut the manifold110 without the aid of an adhesive or another attachment device. Also,the first barrier layer 112 may be coupled to the manifold 110. As usedherein, the term “coupled” includes coupling via a separate object andincludes direct coupling. The term “coupled” also encompasses two ormore components that are continuous with one another by virtue of eachof the components being formed from the same piece of material. Also,the term “coupled” may include chemical, such as via a chemical bond,mechanical, thermal, or electrical coupling. Specific non-limitingexamples of the techniques by which the first barrier layer 112 may becoupled to the manifold 110 include welding (e.g., ultrasonic or RFwelding), bonding, adhesives, cements, or other coupling techniques ordevices.

The manifold 110 and the first barrier layer 112 are disposed within asealed space 118 that is formed by a drape 120 that covers both themanifold 110 and the first barrier layer 112. The sealed space 118 thatis formed by the drape 120 helps to maintain a therapeutic reducedpressure at the tissue site 106 and may include various components, suchas the manifold 110 and the first barrier layer 112.

The drape 120 may be any material that provides a fluid seal. The drape120 may, for example, be an impermeable or semi-permeable, elastomericmaterial. “Elastomeric” means having the properties of an elastomer. Itgenerally refers to a polymeric material that has rubber-likeproperties. More specifically, most elastomers have ultimate elongationsgreater than 100% and a significant amount of resilience. The resilienceof a material refers to the material's ability to recover from anelastic deformation. Examples of elastomers may include, but are notlimited to, natural rubbers, polyisoprene, styrene butadiene rubber,chloroprene rubber, polybutadiene, nitrile rubber, butyl rubber,ethylene propylene rubber, ethylene propylene diene monomer,chlorosulfonated polyethylene, polysulfide rubber, polyurethane, EVAfilm, co-polyester, and silicones. Specific examples of the drape 120include a silicone drape, 3M Tegaderm® drape, or a polyurethane drapesuch as one available from Avery Dennison of Pasadena, Calif.

An adhesive 121 may be used to hold the drape 120 against a patient'sepidermis 138 or another layer, such as a gasket or additional drape.The adhesive 121 may take numerous forms. For example, the adhesive 121may be a medically acceptable, pressure-sensitive adhesive that extendsabout a periphery 129 of the drape 120.

Reduced pressure is delivered to the sealed space 118 via areduced-pressure interface or a connector 122. The connector 122 is atleast partially disposed in an aperture 124 of the drape 120. Theconnector 122 may be held against the drape 120 using a second drape 126that is held against the drape 120 using an adhesive 128. The adhesive128 may be the same or similar to the adhesive 121 that is used to holdthe drape 120 against the patient's epidermis 138. The second drape 126can also be held against the connector 122 using an adhesive (notshown). In one illustrative embodiment, the connector 122 is a T.R.A.C.®Pad or Sensa T.R.A.C.® Pad available from KCI of San Antonio, Tex.

A reduced-pressure conduit 130 is used to deliver reduced pressure fromthe reduced-pressure source 102 to the connector 122. Thereduced-pressure conduit 130 may include one or a plurality of lumens,each of which is capable of transferring reduced pressure or fluid. Amedial portion 131 of the reduced-pressure conduit 130 may have one ormore devices, such as a representative device 132. For example, thedevice 132 may be a fluid reservoir, or collection member, to holdexudates and other fluids removed from the tissue site 106. Otherexamples of the device 132 that may be included on the medial portion131 of the reduced-pressure conduit 130, or otherwise fluidly coupled tothe reduced-pressure conduit 130, include the following non-limitingexamples: a pressure-feedback device, a volume detection system, a blooddetection system, an infection detection system, a flow monitoringsystem, or a temperature monitoring system. Some of these devices may beformed integrally to the reduced-pressure source 102. For example, areduced-pressure port on reduced-pressure source 102 may include afilter member that includes one or more filters, e.g., an odor filter.Multiple devices 132 may be included.

The reduced-pressure source 102 may be any device for supplying areduced pressure, such as a vacuum pump, wall suction, or other source.While the amount and nature of reduced pressure applied to the tissuesite 106 will typically vary according to the application, the reducedpressure will typically be between −5 mm Hg and −500 mm Hg and moretypically between −100 mm Hg and −300 mm Hg.

The first barrier layer 112 is formed from a desolidifying material.“Desolidifying material” means a material operable to desolidify in thepresence of fluid, such as a liquid. Desolidification allows fluidcommunication to occur where the desolidifying material hasdesolidified. Desolidification in this context includes dissolving,degrading, breaking apart, increasing fluid permeability, ortransitioning from a solid to a liquid or other state, including a gelor gas. In some embodiments, the desolidifying material is removed ordissolved in the presence of liquid and in other embodiments thedesolidifying material remains in part but allows fluid communication.

The first barrier layer 112 may be a flexible layer capable ofconforming to the contours of the tissue site 106 and desolidifying inthe presence of a fluid—typically a liquid. Non-limiting examples ofmaterials from which the first barrier layer 112 may be formed includestraight-chain polymers and a variety of water-soluble films, such aspolyvinyl alcohol, polyethylene oxide, cellulose derivatives, such asthe sodium salt of carboxy methyl cellulose, polyvinyl pyrrolidone, oracrylics, such as polyacrylic acid, salts of polyacrylic acid, hydroxyland carboxyl substituted polymers, and copolymers of acrylics andpolyurethanes and their salts. The first barrier layer 112 may also beformed using a bioabsorbable material that relies on biologicalabsorption to desolidify the first barrier layer 112. Such bioabsorbablematerials may desolidify in the presence of biological material presentat the tissue site 106, including particular biological groups thatpromote healing in the wound 107.

According to another illustrative, non-limiting embodiment, inoperation, the dressing 104 is applied to the tissue site 106 of thepatient 108 such that the first barrier layer 112 is adjacent orabutting the tissue site 106 and may be adjacent to a portion of thepatient's intact epidermis 138 as shown in FIG. 1A. When the dressing104 is applied to the tissue site 106 of the patient 108, the firstbarrier layer 112 may be brought into the presence of or into contactwith a fluid, including a liquid. The source of this fluid is describedin further detail below. The fluid desolidifies a first portion 133 ofthe first barrier layer 112 to form a treatment aperture 134 in thefirst barrier layer 112 as shown in FIGS. 1B and 1C. The first barrierlayer 112 may desolidify, at least partially, by dissolving when exposedto the fluid. The treatment aperture 134 exposes the manifold 110 to thetissue site 106 such that fluid communication is provided between themanifold 110 and the tissue site 106. In this way, reduced pressure fromthe reduced-pressure source 102 may be applied to the tissue site 106through the treatment aperture 134.

A second portion 136, or intact portion, of the first barrier layer 112remains intact and does not desolidify when the reduced pressure isapplied to the tissue site 106. The second portion 136 separates themanifold 110 from the epidermis 138 of the patient 108 and can preventor reduce irritation of the patient's epidermis 138 caused by themanifold 110. The first barrier layer 112 can have a smoothinward-facing surface 135 that facilitates the inward migration ofhealthy skin toward the wound 107 in the direction of arrow 140. Thus,the first barrier layer 112 encourages epithelialization of the wound107. Also, the first barrier layer 112 may have a moisture-vaportransmission rate (MVTR) that helps to prevent maceration of the portionof the patient's epidermis 138 that touches the second portion 136 ofthe first barrier layer 112. Using the illustrative embodiments, thedressing 104, and in particular the manifold 110 and the first barrierlayer 112, need not be cut to fit the wound 107 because these componentsmay overlay tissue surrounding the wound 107, such as the patient'sepidermis 138, without unwanted maceration or irritation.

The fluid that causes the desolidification of at least a portion of thefirst barrier layer 112 may come from any of a variety of sources. Forexample, when reduced pressure is applied to the wound 107, exudate fromthe wound 107 may be drawn toward the first barrier layer 112 asindicated by the arrows 142. The exudate may then desolidify the firstportion 133 of the first barrier layer 112 with which the exudate comesinto contact to create the treatment aperture 134. In another,illustrative, non-limiting embodiment, a gel (not shown) may be appliedto the tissue site 106 or the wound 107 prior to applying the dressing104 to the tissue site 106. The gel, which may be a water-based gel, maythen act to desolidify the first portion 133 of the first barrier layer112 with which the gel comes into contact. In yet another illustrative,non-limiting example, fluid may be provided to the dressing 104, and inparticular the first barrier layer 112, by a fluid source (not shown)that supplies fluid through the reduced-pressure conduit 130. In oneembodiment, the device 132 may act as the fluid source.

The dressing 104 may be used on both dry and wet tissue sites. In theexample in which the first barrier layer 112 is used on a relatively drytissue site, the first barrier layer 112 may be formed from a materialthat desolidifies in the presence of a lower amount of fluid.Alternatively, a gel, including a water-based gel, or colloid may beapplied to the relatively dry tissue site before applying the dressing104, and this pre-applied gel will cause the first barrier layer 112 todesolidify. In the contrasting case in which the tissue site 106 isrelatively moist, the first barrier layer 112 may be formed from amaterial that desolidifies in response to larger amounts of fluid.

In another illustrative, non-limiting embodiment, the first barrierlayer 112, when brought into the presence of a fluid, may first turninto a gel before desolidifying into a liquid. The gel formed during thetransition period between the solid and liquidified first barrier layer112 may contain healing agents that are released into the wound 107.Examples of the healing agents that may be released from this gelinclude ionic groups, antimicrobials, anti-inflammatory factors, andgrowth factors. Other healing factors that are beneficial to thecondition of the wound 107 or epidermis 138 and that encourageepithelialization may also be included in the gel. When the firstbarrier layer 112 desolidifies into a liquid, the liquid may be drawnthrough the manifold 110 and out of the dressing 104 using the reducedpressure that is supplied by the reduced-pressure source 102.

In other illustrative, non-limiting embodiments, additional layers maybe added to the sealed space 118. For example, an absorbent layer,another manifold layer, another barrier layer, or other layers orcomponents that facilitate reduced-pressure therapy may be included inthe dressing 104 and disposed in the sealed space 118.

Referring now primarily to FIG. 2, another illustrative, non-limitingembodiment, the manifold 110 includes two surfaces 144 and 146 coveredby the first barrier layer 112 and a second barrier layer 148,respectively. The first barrier layer 112 and the second barrier layer148 may be formed from the same or different materials. In the examplein which the first and second barrier layers 112, 148 are formed from asame or similar material, a caregiver may pay little or no regard towhether the first barrier layer 112 or the second barrier layer 148 isdeployed adjacent to the tissue site, e.g., the tissue site 106 inFIG. 1. In the example in which the first and second barrier layers 112,148 are different, however, a caregiver may choose between placingeither the first or second barrier layers 112, 148 against the tissuesite 106 based on the properties of each barrier layer 112, 148. Thefirst and second barrier layers 112, 148 may each have differentproperties that are adapted for treating different types of wounds orconditions. For example, the first barrier layer 112 may be formed froma material that requires less fluid to desolidify than the secondbarrier layer 148. In this example, the first barrier layer 112 may beused for relatively drier wounds than the wounds for which the secondbarrier layer 148 is used.

The first and second barrier layers 112, 148 may also differ in otherrespects. For example, the first and second barrier layers 112, 148 mayeach respectively contain different healing agents that are adapted fordifferent tissues or wound types. The first and second barrier layers112, 148 may also each have a different moisture vapor transmissionrates, hardness, smoothness, thickness, or other properties. In anotherillustrative, non-limiting example, either or both of the first andsecond barrier layers 112, 148 may be partially or wholly formed from adebridement material that encourages debridement at the tissue sitethrough autolytic mechanisms. Either or both of the first and secondbarrier layers 112, 148 may also be able to release debridement agents(e.g., enzymes) that break down tissue, such as eschar and necrotictissue. In another illustrative, non-limiting embodiment, each lateralside 150, 152 of the manifold 110 may also be covered by a barrierlayer.

Referring now primarily to FIG. 3, a first barrier layer 154 havingperforations 156 covers a first surface 144 of a manifold 110. Theperforations 156 in the first barrier layer 154 provide immediate fluidcommunication between the manifold 110 and a tissue site when thedressing associated therewith is applied to the tissue site. Thus,reduced pressure may be applied to the tissue site, via the perforations156, before the first barrier layer 154 desolidifies. The perforations156 may be uniform or non-uniform in size and may take any shape. Theperforations 156 may be engulfed, or simply disappear, when the firstbarrier layer 154 desolidifies.

In another illustrative, non-limiting embodiment, the second barrierlayer 148 may also include a plurality of perforations (not shown). Inthis embodiment, the percentage of the total surface area of each of thefirst and second barrier layers 154, 148 that is occupied by theperforations in each of these barrier layers 154, 148 may differ. Forexample, the first barrier layer 154 may have a higher density ofperforations 156 than the second barrier layer 148. The perforations 156in the first barrier layer 154 may also be larger or smaller than theperforations in the second barrier layer 148.

The perforations in each of the first and second barrier layers 154, 148may also provide different fluid flow rates for each of these barrierlayers before or during the time at which they desolidify. In thisexample, the perforations 156 in the first barrier layer 154 provide aflow rate X across the first barrier layer 154 for a given fluid andreduced pressure, while the perforations in the second barrier layer 148provide a flow rate Y across the second barrier layer 148 for the samefluid and reduced pressure. The flow rate Y may be the same as orgreater than X. By differing the flow rates between the first and secondbarrier layers 154, 148, each of these barrier layers may be used forparticular types of wounds. In the example in which the second barrierlayer 148 has a flow rate Y greater than the flow rate X in the firstbarrier layer 154, the second barrier layer 148 may be suited forplacement adjacent to wounds that are drier wounds. These aforementionedembodiments that include differing barrier layers on different sides ofthe manifold 110 allow a caregiver to provide two treatment scenarioswith a single dressing.

Although the present invention and its advantages have been disclosed inthe context of certain illustrative, non-limiting embodiments, it shouldbe understood that various changes, substitutions, permutations, andalterations can be made without departing from the scope of theinvention as defined by the appended claims. It will be appreciated thatany feature that is described in connection to any one embodiment mayalso be applicable to any other embodiment.

We claim:
 1. A system for providing reduced-pressure therapy to a tissuesite of a patient, the system comprising: a reduced-pressure source forsupplying reduced pressure; a manifold having a first, inward-facingsurface and a second surface, the manifold operable to transfer thereduced pressure; a first barrier layer covering at least a portion ofthe first, inward-facing surface of the manifold, the first barrierlayer comprising a first portion and a second portion formed from adesolidifying material; and a drape for covering the second surface ofthe manifold and a portion of the patient's epidermis to provide asubstantially sealed space containing the manifold and the first barrierlayer; wherein the first portion is adapted to desolidify and form atreatment aperature under reduced pressure, while the second portion isadapted to separate the manifold from epidermis adjacent to the tissuesite and remain intact under reduced pressure.
 2. The system of claim 1,further comprising: a second barrier layer covering the second surfaceof the manifold, the second barrier layer operable to desolidify in thepresence of fluid to expose the manifold.
 3. The system of claim 1,further comprising: a second barrier layer covering the second surfaceof the manifold, the second barrier layer operable to desolidify in thepresence of fluid to expose the manifold to the tissue site, wherein thesecond barrier layer desolidifies at a faster rate than the firstbarrier layer when in the presence of the fluid.
 4. The system of claim1, wherein the first barrier layer is formed with a plurality ofperforations for providing fluid communication across the first barrierlayer.
 5. The system of claim 1, wherein the first barrier layercomprises a first plurality of perforations for providing fluidcommunication across the first barrier layer, and further comprising: asecond barrier layer on the second surface of the manifold, the secondbarrier layer comprising a second plurality of perforations forproviding fluid communication across the second barrier layer.
 6. Thesystem of claim 1, wherein the first barrier layer comprises a firstplurality of perforations for providing a flow rate (X) across the firstbarrier layer, and further comprising: a second barrier layer on thesecond surface of the manifold, the second barrier layer comprising asecond plurality of perforations for providing a flow rate (Y) acrossthe second barrier layer, wherein Y is greater than X.
 7. The system ofclaim 1, wherein the first portion of the first barrier layer isoperable to desolidify into a liquid when contacting a fluid.
 8. Thesystem of claim 1, wherein the desolidifying material becomessubstantially fluid permeable in the presence of a liquid.
 9. Anapparatus for providing reduced-pressure therapy to a tissue site of apatient, the apparatus comprising: a manifold having a first,inward-facing surface and a second surface, the manifold operable totransfer reduced pressure; and a first barrier layer covering at least aportion of the first, inward-facing surface of the manifold, the firstbarrier layer comprising a first portion and a second portion formedfrom a desolidifying material; wherein the first portion is adapted todesolidify and form a treatment aperature under reduced pressure, whilethe second portion is adapted to separate the manifold from epidermisadjacent to the tissue site and remain intact under reduced pressure.10. The apparatus of claim 9, further comprising: a second barrier layercovering the second surface of the manifold, the second barrier layeroperable to desolidify in the presence of a fluid to expose the manifoldto the tissue site.
 11. The apparatus of claim 9, further comprising: asecond barrier layer covering the second surface of the manifold, thesecond barrier layer operable to desolidify in the presence of a fluidto expose the manifold to the tissue site, and wherein the secondbarrier layer desolidifies at a faster rate than the first barrier layerwhen in the presence of the fluid.
 12. The apparatus of claim 9, whereinthe first barrier layer comprises a plurality of perforations providingfluid communication across the first barrier layer.
 13. The apparatus ofclaim 9, wherein the first barrier layer comprises a first plurality, ofperforations for providing fluid communication across the first barrierlayer, and further comprising: a second barrier layer on the secondsurface of the manifold, the second barrier layer comprising a secondplurality of perforations for providing fluid communication across thesecond barrier layer.
 14. The apparatus of claim 9, wherein the firstbarrier layer comprises a first plurality of perforations for providinga flow rate (X) across the first barrier layer, and further comprising:a second barrier layer on the second surface of the manifold, the secondbarrier layer comprising a second plurality of perforations forproviding a flow rate (Y) across the second barrier layer, wherein Y isgreater than X.
 15. The apparatus of claim 9, wherein the first barrierlayer is operable to desolidify into a liquid when contacting the fluid.16. The apparatus of claim 9, wherein the first barrier layer includes ahealing agent, and wherein the healing agent is released as the firstbarrier layer desolidifies.
 17. A method for providing reduced-pressuretherapy to a tissue site of a patient, the method comprising: applying afirst portion and a second portion of a barrier layer over the tissuesite, wherein the second portion is applied to epidermis adjacent to thetissue site; applying a manifold over the barrier layer such that thesecond portion of the barrier layer is disposed between the manifold andthe epidermis; desolidifying the first portion to create a treatmentaperture while the second portion remains intact; and applying a reducedpressure to the tissue site via the treatment aperture.
 18. The methodof claim 17, wherein applying the reduced pressure to the tissue siteincludes drawing a desolidified portion of the barrier layer materialout of the dressing via the manifold.
 19. The method of claim 17,further comprising: applying a fluid to the dressing from a fluid sourceto facilitate the desolidification of the barrier layer.
 20. The methodof claim 17, further comprising covering the manifold and the barrierlayer with a drape to provide a substantially sealed space containingthe manifold and the barrier layer.